1. Field of the Invention
The present invention relates to spray gun technology and more particularly, to an improved structure of gyrating nozzle head spray gun, which comprises a grip, an attachment tube connected to the grip, and a gyrating nozzle head assembly connected to the grip and surrounded by the attachment tube for ejecting compressed air in a spiral pattern.
2. Description of the Related Art
FIGS. 6 and 7 illustrate a gyrating nozzle head spray gun. The gyrating nozzle head spray gun generally comprises a grip A, a gas-delivery tube A1 connected to one end of the grip A, a water tank A11 detachably connected to a bottom side of the gas-delivery tube A1, a dip tube A12 dipped in water in the water tank A11, a water-supply tube A13 connected to the top end of the dip tube A12 and axially inserted through the gas-delivery hole A10 of the gas-delivery tube A1, and a gyrating nozzle head assembly B. The gyrating nozzle head assembly B comprises a gas-supply tube B1 connected to the gas-delivery tube A1 and defining therein a gas-supply hole B10, a gyrating nozzle head B2, and a bearing B3 supporting the gyrating nozzle head B2 on a connection portion B11 at the distal end of the gas-supply tube B1. The gyrating nozzle head B2 comprises a gas accumulation chamber B20, a through hole B21 located at the center of the front side thereof in communication with the gas accumulation chamber B20 and an oblique jet hole B22 in communication with the gas-supply hole B10. The water-supply tube A13 has a water outlet end A131 inserted through the gas accumulation chamber B20 of the gyrating nozzle head B2 and the through hole B21. Further, the diameter of the through hole B21 is larger than the outer diameter of the water outlet end A131 so that a clearance is defined between the through hole B21 and the water outlet end A131 of the water-supply tube A13. The air inlet A2 of the grip A is connected to an external air compressor using a gas tube A21. Thus, the user can operate the trigger A3 of the grip A to open the air inlet A2 of the valve seat A4 for letting compressed air flow through the gas-delivery hole A10 of the gas-delivery tube A1 into the gas-supply hole B10 of the gas-supply tube B1 of the gyrating nozzle head assembly B and the gas accumulation chamber B20 of the gyrating nozzle head B2 for ejecting out of the oblique jet hole B22 and forcing the gyrating nozzle head B2 to rotate on the bearing B3. When compressed air is guided into the gas-supply tube B1 and the through hole B21 of the gyrating nozzle head B2, water is sucked in the dip tube A12 from the water tank A11 and guided through the water-supply tube A13 toward the opposite water outlet end A131 and the through hole B21 of the gyrating nozzle head B2. At the same time, compressed air is ejected out of the gas accumulation chamber B20 through the clearance between the through hole B21 and the water outlet end A131 of the water-supply tube A13 and the oblique jet hole B22 of the gyrating nozzle head B2 to turn the ejected flow of water into a mist of fine droplets.
When the dip tube A12 delivers water from the water tank A11 into the water-supply tube A13 for ejection through the water outlet end A131 of the water-supply tube A13 and the through hole B21 of the gyrating nozzle head B2, compressed air is simultaneously ejected out of the gas accumulation chamber B20 and oblique jet hole B22 of the gyrating nozzle head B2, causing rotation of the gyrating nozzle head B2 on the bearing B3 at a high speed. During high speed rotation of the gyrating nozzle head B2, the water outlet end A131 is forced by the high pressure of the compressed air in the gas accumulation chamber B20 to vibrate in the through hole B21. Vibration of the water outlet end A131 causes the water outlet end A131 to rub against the through hole B21. Because the gyrating nozzle head B2 is a metal member and the water-supply tube A13 is a flexible plastic member, vibration of the water outlet end A131 of the water-supply tube A13 to wear against the peripheral wall of the through hole B21 can wear the water outlet end A131, affecting the performance of the gyrating nozzle head spray gun. Therefore, it is desirable to provide a gyrating nozzle head spray gun that eliminates the aforesaid problem.